Stephanie Scott's killer had another target that day: A 12-year-old girl.

When police found the body of NSW school teacher Stephanie Scott last April, the horrific case became a staple of news bulletins and front pages around the country. But it’s now been revealed that those headlines could have turned out very differently.

According to The Daily Telegraph, Scott’s self-confessed killer, school cleaner Vincent Stanford had actually planned to abduct and kill a schoolgirl when he stumbled across the 26-year-old working overtime on Easter Sunday, 2015.

On Wednesday, the 25-year-old appeared via video link from Sydney’s Long Bay jail, where he pleaded “guilty” to aggravated sexual assault and murder, as Scott’s mother and sister watched on from the public gallery.

Disturbing new details have emerged about the man who murdered New South Wales teacher Stephanie Scott last year. https://t.co/OZJQUJqcnu

The Daily Telegraph reports Stanford’s intended target was a 12-year-old who lived in the Leeton area and was often seen near the gates of the school where he and Scott worked.

He had reportedly planned to attack the child that weekend, but she happened to be away on a family trip.

Instead, Stanford came across Scott preparing lessons for her English and drama classes ahead of her upcoming honeymoon to Tahiti.

Sometime after midday that day, April 5, Stanford raped and murdered her inside a staffroom, in one of the most brutal attacks NSW police have ever seen.

Stephanie Scott with her fiancé, Aaron Leeson-Woolley. via Facebook.

When Scott didn't return home that evening, her fiancé Aaron Leeson-Woolley called police to report her missing. Three days later Stanford was arrested after police found a camera with pictures of a burned body.

Scott's remains were eventually discovered 70km from the school, in Cocoparra National Park, on April 10, just two days before she was due to be married.